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Flashcards in Introduction Deck (25):
1

What does the prognosis of bone cancer depend on?

  • Overall Stage
  • Presence of Metastasis
  • Skip ( discontinuous) lesion within the same bone
  • Histologic grade
  • tumour size

2

Name a staging system?

  • Enneking
  • the musculoskeletal tumour society system
  • Most popular for orthopaedic surgeons
  • Two systems- one for benign & one for malignant
  • Malignant lesion used Roman numerials I,II III
  • Benign lesions use Arabic numbers 1,2,3

3

Dsecribe the enneking staging system for malignant tumours?

Stage IA

  • Low grade
  • T1 intracompartmental 
  • Mo no mets

Stage IB

  • Low grade
  • T2- Extracompartmental 
  • Mo - no mets

Stage IIA

  • High grade
  • T1- Intracompartmental
  • Mo- no mets

Stage IIB

  • High grade
  • T2- Extracompartmental
  • Mo- no mets

Stage IIIA

  • Metastatic
  • T1- intracompartmental 
  • M1- regional or distant mets

Stage  III B

  • Metastatic
  • T2- extracompartmental
  • M1- mets distant or regional

4

What are difference between tumour compartments?

  • Intracompartmental
    • bone tumours confined within cortex of the bone
  • Extracompartmental 
    • Bone tumours extend beyond the bone cortex

5

What are the differences between high and low grade tumours?

  • Histologically , tumours graded based on percentagee of cellular atypia
  • Low grade tumours
    • ​Low metastatic potential
  • High grade tumours
    • Greater metastatic potential 

6

Can you describe the numbering for benign tumours?

  1. Latent lesion - non osssifying fibroma
  2. Active lesion- ABC, chondroblastoma
  3. Agressive lesion- GCT of bone

7

What is the criteria to predict the risk of pathological fx?

  • the presence of significant functional pain
  • >50% destruction of cortical bone

  • Formal staging systems 


    • Mirel criteria 




    • Harington criteria
       

8

Why is prophylatic fixation of fx preferred to fixation of pathological fx?

  • Shorter operation time
  • Decreased Morbidity
  • Quicker recovery

9

Describe the Harington criteria?

  • >50% destruction of diaphyseal cortices
  • >50-75% destruction of metaphysis (>2.5cm)
  • Permeative destruction of subtrochanteric femoral region
  • Persistent pain following irradiation

10

Describe the Mirel criteria?

  • Score >8 = prophylatix pinning
  • score divided into 
    • Site
      • Upper limb (1), Lower lImb (2), Peritrochanteric (3)
    • Pain
      • Mild (1), Moderate (2), severe (3)
    • Lesion 
      • Blastic (1), Mixed (2) , Lytic (3)
    • Size
      • <1/3 (1), 1/3-2/3 (2), >2/3 (3)

11

What is the tx logarthim for a Path fx  ?

  • Obtain tissue diagnosis
    • Unless pt has known primary neoplasm w bone biopsy proven skeletal mets, the treating surgeon should biopsy lesion in question
    • biopsy may require separate incision used for im nailing of bone
    • if biopsy suggests primary neoplasm ( like sarcoma) may benefit from neoadjuvant chemo/radiotx then close wound & refer to local sarcoma centre prior to stabilisation- as surgical tx will contaminate entire bone w sarcoma and affect ability to preform limb salvage
  • Surgical Fixation
    • ​don't proceed unless primary neoplasm ruled out.
    • goals of fixation
      • maximise ability to immediate mobilistion & WB.
      • Protect entire bone in setting of systemic /met disease
      • Optimise implant choice in content of pt;s overall prognosis
      • Type of fixation depends on site of lesion
        • ​hemi for femoral neck/im nail for peritrochanteric
  • ​​​Post op radiation
    • ​refer to oncologist for post op radiotx to 
      • ​decrease pain
      • slow progression
      • tx remaining burden not removed in surgery

12

What cancers have the worse life expectancy?

  • Lung cancer
  • Melanoma 
  • < 6months and <5% 5 yr survival when bone mets are present

13

Where is the common site for all boney mets?

  • The spine

14

Where is the common site for pathological fracture secondary to metastasis in bone?

  • Proximal femur
  • femur is most common long bone assoc with mets disease 
  • the stress risers around the proximal femur make it vunerable to fx

15

What is the mechanism of chemotherapy?

  • It induces Apoptosis
    • ​= programmed cell death
  • may target specific proteins over expressed in cancer cells
    • e.g. tyrosine kinase inhibitors block tyrosine kinase receptos overexpressed  in neoplastic cancer cells - herceptin in breast cancer
  • elimates micrometastasis in lungs
  • >98% necrosis with chemotherapy is good prognostic sign

16

Describe the important of resistance to chemotherapy

  • Expression of multi- drug resistant (MDR) gene portends very poor prognosis
    • cells can pump out chemotherapy out of cell
    • present in 25% of Primary lesion and 50% metastatic lesion

17

What are the indications to use chemotherapy?

  • Integral component of tx along with surgical resection in 
    • Osteosarcoma ( Intramedullary /periosteal)
    • Ewing's sarcoma 
    • Primary neuroectodermal tumour
    • Malignant fibrous histocytoma
    • Dedefferentiated chondrosarcoma
    • Chemotherapy for soft tissue sarcoma is contraversial

18

What is the administration of chemotherapy ?

  • Preoperative- neoadjuvant- given for 8-12 weeks
  • Post operative given for 6-12 months

19

Can you name a chemotherapy agent and its side effects?

  • Doxorubicin
    • is an anthracylcine antibiotic commonly used in oncological protocols- tx osteosarcoma
    • Inhibits DNA/RNA synthesis and blocks topoisomerase II=> apoptosis
    • functions as a cytostatic agent
  • Side effct
    • cardiac toxicity-> cardiomyopathy
    • dexrazone- drug protective against cardiac effects of doxorubicin
  • ​Cyclophospphamide- SE = myelosuppression/ urotoxicity

***chemo targets rapidly dividing cells - so also lining the gut, bone marrow, hair and skin

20

What is  radiotherapy's mode of action? 

  • Production of free radicals
  • direct genetic chnage

21

What are the indications for radiotherapy?

  • Definitive control of primary malignant bone tumours
    • Ewing's sarcoma
    • Primary neuroectodermal toumour
    • Hemangioendoelioma
    • solitary plasmacytoma of bone
  • Adjuvant to surgical excision
    • soft tissue sarcoma
    • given pre/post surgical excision
  • Palliative care & impending fracture fixation
    • mets bone disease
    • require to reduce overall tumour burden
    • prostate cancer are very radiosensitive
    • breast cancer is 70% sensitive, 30% Resistant
    • Gi and renal are not radiosensitive

22

What is the typical dose of radiotherapy?

  • I rad= IcentiGray
  • Typical dose = 180-200 cGy/day
  • radiation is given in fractions as radiotherapy is accumulative
  • the total dose is summuation of all the separate fractions given during tx
  • <45 gray => uncomplicated tissue healing
  • 45-55= usually heals with no problems
  • >60 Gray= tissue not likely to heal

23

What are the complications of radiotherapy?

  • Early effects
    • delayed wound healing
    • infection
    • desquamation
  • Late effects
    • fibrosis
    • joint stiffness
    • secondary sarcoma
    • fractures

24

Describe the epidemiology of post radiation sarcoma?

  • defined by the development of sarcoma in a region previosuly radiated for malignancy
  • inicidence 13%
  • more frequent in pts prior to chemotherapy
  • overall pt prognosis is poor

25

Describe the epidemiology of post radiation fx?

  • Approx 25% incidence following soft tissue sarcoma resection and external beam irradiation
  • risk factors
    • female
    • anterior femoral compartment resection
    • age >50 yrs
    • periosteal stripping
    • radiation dose >60 Gy
    • osteoporosis